Rivet pin cutters



United States Patent RIvEr PIN cUTTERs Kenneth L. Anacker, Kirkland,Wash., assignor to I loeing Airplane Company, Seattle, Wash., acorporation of Delaware Application September 24, 1953, Serial No.382,164

s claims. (ci. so-s's) Blind rivets are extensively used in aircraftconstruction, and commonly include an exteriorly headed hollowshankedrivet and a pin having a head on its interior end that bears on theinterior end of the rivet shank, and a shank which projects through thehollow shank'of the rivet itself, to be engaged and drawn outwardly,whereby l to expand the interior end of the hollow shank. There remainsthe exteriorly projecting end of the rivet pin, which must be broken oior cutoff in some way, not only to leave the surface free from suchobstructions butto avoid their drag elect in locations Vwhere they areexposed f to the airstream. It is also desirable that the cut end of therivet be peened in some manner in order to insure that it will not slipback into the interior of the aircraft structure, leaving a hole throughthe rivet which will permit entrance of moisture and dirt, and which initself may add to the drag. Where the elimination of drag is of majorimportance, as it is in almost all exterior surfaces, it is highlydesirable that the shank of the rivet pin be cut in such manner that itis precisely flush with the exterior surface of the riveted structure,and approximation, only, of that objective is virtually as objectionableas if the rivet pin were left uncut.

The present invention provides a tool by which these several objects mayall be attained readily, simply, and quickly, without any large degreeof skill on the partof the operator, and in particular without applyinga stress 2,717,440 Patented Sept. 13, 1955,E

lice forces directed axially of the rivet pin `shank are substantiallyequally balanced and so are negligible, there is to all intents andpurposes'no force applied to the riveted structure. Since the cuttingelements actv at the extreme lower end of the tool, the severance ofvthe rivet pinV shank can be made to occur in the plane of therivetshead, or if it be a ush head, then in the plane of the exterior lsurfaceof the riveted structure itself.

The invention will be best understood by reference to the accompanyingdrawings in which`the invention is illustrated in a practicable form,such as is` presently preferred by me.

Figure 1 is a side elevational view 'of the operating parts of the tool,certain of the parts and the riveted structure itself being shown insection for better illustration. Parts in this View are in the passiveorinitial starting position. Figure 2 is anend elevation of the tool, withthe lpal-'ts in the position in which they are shown in Figure 1.

Figure 3 is a view corresponding to Figure l but with the parts shown inthe position they would assume substantially at the conclusion of thepin-,cutting operation.

Figure 4 is a View corresponding to Figure 2, but showing parts in thepositions corresponding to Figure 3. Figure 5 is an axial sectional viewon the plane indicated by the line 5 5 of Figure 3. l

v A rotative supporting bodyl 4 is formed with an enlarged head and witha stem V41, the latter being'arranged for driving engagement with therotative shaft of an electric drill or thelike. The lower end of thedrill housing is represented at 5,y and the interconnection between themis represented by the yscrew-threaded stern 50, screwed within athreaded axial borein the stem 41 of the tool. The particular manner ofconnection to the Adrill is immaterial to the present invention, andthat shown is intended as typical only. v Y For convenience ofreference, the head V40 of the rotative supporting body 4 willbedescribedas its lower to the structure which has been riveted, for whileprior attempts have approached the aims indicated above, though have notattained them completely, such prior attempts have in all instancesknown to meapplied undue stress to theriveted structure, tending todeform it, andgit is a particular vobject of the present invention toaccomplish the primary aims indicated without at'the same 'time applyingany appreciable stress Vto theriveted structure.

Likewise it-is an object to provide a tool of this lsort which may beemployed in conjunctionwith `aconventional electric drill or thelike,-t'o which the tool 'can be attached, so that the operation can beperformed-simply and quickly, by tool-driving means which are valwaysreadily available. y v j y The invention comprises in effect a pluralityof levers, eachpivotally mounted in a particular kmanner upon a rotativesupporting body, and each formed at a lower end with a combined pointedand chisel-likevcutting element, the whole so organized and arrangedthat the several cutting elements, by pivoting, may simultaneouslyapproach and meet in the axis of rotation, but `maybe swung laterallyaside therefrom; when thus mutually swung aside they may embrace theprotruding rivet pin symmetrically, and may then be urged inwardlyduring rotation, whereby ltoy complete severance of the rivet pin asthey reach the axis of rotation. The'rotative action and the formationof the cutting-elements are such that during rotation they peen the cutend of the rivet pinshank to insure its retention in the axial bore ofthe hollow rivet. Since the forces applicable to the rivet pin shank aredirected almost wholly radially of ax'is,-`and the end. .This lower endis exteriorly providedwith several llat portions 42 which are inclinedsomewhat` with respect to the axis of rotation. These several ats42 arespaced equally or symmetrically about the axis of the head4 40, and oneach thereof is pivotally mounted a leveril. In the tool illustratedthere are 'three such levers. It ,isfpossible to use only two, but theuse of three is preferred since it affords the possibility ofbracketing'the rivet jpinfwith complete equalization of forces,laterdescribed, directed radially inwardly of the pins axis. ,More`than-'three levers may be used, also, but again theuse Iof,lthreeiassures equalization of forces, whereas fo'ur wouldI not, in thesame automatic sense. Moreover, the toolis small, and there is not roomfor-allarge number. Each such lever is pivotally'r'nounted, as ,b'yfaVpivot bolt `10, the axis of which is-directied more or lessradiallj'I ofthe rotative axis, and normal to the flattened portion 42 of the head onwhich'the leveris pivoted, but which by reason of the inclination oftheat 4 2y is caused to assume a slight inclination with respect to aplane normal t0 the rotative axis of the supporting body 4.. "All suchpivot bolts are inclined in the same direction with respect to thataxis, and of course. all suchk pinsare equally or symmetrically spacedabout the rotative axis.v Exceptfor their inclination they arepreferably normal' to that axis. The levers 1LA are in'etfect bellcranklevers, hai/ing a downwardly directedpointed end terminating inachisellike cutting element 11. lThe upper end of each lever 'isdirected laterally from the pivot-bolt at 10, and terminates in a heel12. The heels Vof the several le'versare directed all in the samevrotative sense. The shape'fo'f each lever is such, with respect totheangle of inclination ofthe pivot bolt 10 relative totherotative axis',Ithat the lowerrnost tip of its cutting element 1.1 may exacly reach orpass through the'rotativeaxis of thesupporting body 4, but may also beswung aside laterally from that rotative axis. In Figure 4 the cuttingelements are shown at the instant they arrive at coincidence with therotative axis, whereasin lFigure 2 these. cutting points are shown intheir swung-aside position. The formation of the cutting-element -`issuch asto provide a chisel-like edge, that shown :in contact withl theshank 5 of lthe rivet pin, and with -a downwardlyacing flat surfacewhich, as will be show-n later,acts to peen .the cut end of therivetpin.

The several levers -1 are normally held resiliently in their outwardlyswung or 4separated position, to which end any-.convenient resilientlyyieldable means such as the jtension=springs .2 may .be used. Suchsprings may be engagedv in .any suitable .manner `with the individuallevers 1, as, for example, by securing their opposite ends to -theheel`12 of one lever-andto lthe facing edge of the swt :levee Y v In orderto urge lthe levers in opposition to the springs 2 so asrto swing theircutting elements il inwardly from the outswing 7position of .Figure 2 tothe inal position of Figure 4,.a force is applied to the upper end ofeach such lever -atsthe heel Y12. This Aiorcershould be applied equallyand simultaneously to all the levers. To that end a bushing 3 is mountedupon the stemv 41 of the rotative supporting bodyft, this bushing beingpreferably outwardly tlanged lat its lower end as `indicated at 3i. Itwill rotate with the lrotative body 4, `although no special means areprovided to insure this other than the irictional engagement betweenthem. However, in order to effect axially downward sliding movement ofthe bushing 3, and so to :apply a 'force to the heels 12 of the levers,which contact lthe lower face of the flange 31, two combined rotativeand thrust bearings are conveniently employed. The upper bearing 32 isin etect xed against axial movement relative to the supporting body 4,to which end its outer race may bearV against ,the lower end face of thedrill housing 5, AandA the lower bearing 33 has its inner race lbearingagainst the upper surface of the liange 31, or otherwise operativelyconnected to the bushing 3 to .elect movement of the latter axially ofthe axis of rotation. The inner races of the two bearings, which arespaced somewhat widely apart, are free to rotate, and the outer raceswill remain non-rotative. All may be housed within a surrounding sleeve30.

' A cam-like element 6, which may be simply a square block, isinterposed between the outer faces of the upper and lower bearingsA 32and 33 within the sleeve 30. 'Two diame'trically opposite cams are used,and they may be causedit'o tilt from the position of rest shown inFigure l braces thesl'eeve 30 and 'which connects the two coaxial stubshafts at the diametrically opposite sides of the tool. When ytheyolre61 is tilted about the common axis den'ed by the 'stub shafts 60, theconsequent rotational movement of the cams 6 will force the upper andlower bearings 32, 33 apart, and so will exert pressure on the Vang'e31, which in turn will urge the heels 12 downwardly and thereby produce4an inwardly directed force on the swung-aside cutting'points 11. Suchtilting of the yoke 61 may be accomplished by means of an operatinghandle 62. moving in the direction of the arrow shown in Figure 3. VTheresultant movement of the levers 1 is likewise indicated by arrows inthat ligure and in Figure 4.

V Two thin sheets A and B are shown in the drawings as secured togetherby a blind rivet, consisting of a hollowshank 470 having a ush vhead 71,the interior end of the hollow shank 70 ybeing upsettable by means ofoutward urging of the shank 7 of the rivet pin, which latter 'has anVinterior head 72 bearing upon the inner end of the hollow. shank70. Theriveting operation the -exteriorly protruding. .portion of the shank 7out.

wardly while holding the head 71 against outward movement, it becomesnecessary to sever the protruding end of the pin 7. The tool describedabove is applied to the protruding end of the shank 7, the jaws formedby the cutting elements 11 of the several levers being spread widelyenough to slip over the end of the rivet pin, and these cutting elementsare brought into contact with the head 71 of the rivet. There is no needto press with any particular force against the head 71, merely to placethe cutting Velements 11 in -contact'therewith *Parts are then in thepositions 'shown inl Figures l and 2.

The rotation of the tool is begun, and at the same time the operatinglever 62 isswung in a manner already described to urge the cuttingelements 11 inwardly, where upon their chisel-like inner edges begin tosever the rivet. Their cut is somewhat V-shaped, as seen in Figure 5,and any downward pressure is more than equalized by an accompanyingupward reaction. Moreover, thedownwardly facingttlat surfaces of thecutting elements11 tend to peen the embedded portion of the .pi-n.7, andthis insures its retention within the shank 70. As the cutting operationproceeds, the points of the cutting elements 11 eventually swi-nginwardly about their respective pivot axes defined by the .several'bolts 10, until finally the points of the-cutting elements 11 arrivesimultaneously at .the rotative axis of the tool, thatfis to say,,par-ts `are in the position Ashown :in 'Figures 3 and 4. When thisstage is reached,'the exteriorly protruding portion 7' of the rivet pinis severed and drops off, leaving the cut end of .the -rivet pin 7smoothly ,polished and ush with the head 71 of the rivet, and if that isa flush head, then iiush ywith the exterior surface of the sheet A ofthe riveted Vstructure.- `Throughout the operation the forces vappliedto the `rivet -pin and to the riveted structure are almost solely in thedirection of the plane of the riveted structureand radiallyof the rivetpin, inwardly from three symmetrically lspaced directions'fandconsequently there is no tendency to ldeform the riveted structure nor'any cause to back 'upthe same, which vwould be'impossible in placeswhere blind rivets are employed,

I claim as my invention:

1. A tool for cutting the rivetlpin of -a blind rivet Hush with theexterior end of the rivets head, and for -like purposes, comprising arotative supporting body, a plural, ity of levers -pivotally mountedthereon to swing about pivot axes directed generally radially of theaxis of `rotation and spaced vthereabout, Ibut inclined with respect toa plane normal to that axis, each suchA lever being formed -at itslower'end with a cutting element, and being of such shape and length,with respect to the kinclination of its pivot axis, that its cuttingelement invpivoting can pass transversely through the axis of rotation,and means to exert a force upon the opposite fend of all said levers,during rotation, in a direction to lurge their respective cuttinglelements about theinpivot axes from a laterally swung-aside positiontowards the axis of rotation.

2. A tool as Iand for the purposes indicated in claim -1, andresiliently yieldable means to retain .thellevers normally in thelaterally swung-aside position.

3-. A tool as andforthe purposes indicated in claim l, wherein thepressure-'exerting means includes a bushing carriedfiby andsldableaxially 'alongsaid rotative body, and bearing upon the respectivellevers at the ends opposite the cutting element, means carried yby saidbushing for engagement to move it,:axial1y,- areaction ymember immovableaxiallyI with respect to the supporting body and spacedaxially from saidbushing-carried means, yand means reacting from said reactiontrnemberupon vsaid bushing-carried means, to shift the `bushing, axially, and sotoexert vpressure upon 'said levers.

4. A :tool as'and for the purposesindicatedwin Aclaim l, whereini-.the'cutting 'elements vare feach formed Ywith a chisel-like cutting-2edgedirected inwardly .towardsfthe axis'of rotation and generally transverseto that-axis when partsare-fin: the 'swung-aside1mositionyfwherebyxto.cut

an annular V-notch in the rivet pin shank when urged inwardly, and eachsuch cutting edge terminating in a cutting point which, by the swingingof the several levers each on its pivot axis, is swung into coincidencewith all other such points as each point reaches the rotative axis.

5. A tool for cutting the rivet pin of a blind rivet ush with theexterior end of the rivets head, and for like purposes, comprising arotative supporting body, three levers pivotally mounted thereon toswing about respective pivot axes directed generally radially of andsymmetrically spaced about the axis of rotation, but inclined alike withrespect to a plane normal to that axis, each such lever being formed atits lower end with a pointed cutting element, and being of such lengthand shape otherwise, with respect to the inclination of its pivot axis,that in pivoting its cutting element can swing from a laterallyswung-aside position inwardly to the axis of rotation, and means toexert pressure upon the opposite end of all said levers, duringrotation, to urge their respective cutting elements thus inwardly, allsimultaneously.

6. A tool for cutting the rivet pin of a blind rivet ush with theexterior end of the rivets head, and for like purposes, comprising arotative supporting body, three bell-crank levers pivotally mountedthereon to swing about respective pivot axes directed generally radiallyof and equally spaced about the axis of rotation, but inclined alikewith respect to a plane normal to that axis, each such lever beingformed to define a lower end depending below the supporting body andterminating in a pointed cutting element, and a laterally extendingupper end directed in all instances in the same rotative sense andterminating in a pressure-receiving heel, each levers lower end being ofsuch length and shape, relative to the inclination of its pivot axis,that in pivoting its cutting CFI its ange bearing upon the heels of therespective levers,

and means operative during rotation to urge said bushing axially towardssaid levers, and so to exert pressure upon the levers upper ends, toswing their lower ends inwardly in opposition to said resilientlyyieldable means.

7. A tool as and for the purposes indicated in claim 6, including twocombined rotative and thrust bearings surrounding and spaced axially ofsaid bushing, tiltable cams interposed between said bearings andoperative by tilting to urge the bearings apart from a position ofclosest approach, the upper bearing being axially xed with relation tosaid suporting body, and the lower bearing engaging the bushings flange,and means to tilt said cams to urge the bearings apart, the wholeconstituting the means to urge the bushing axially. t

8. A tool as and for the purpose indicated in claim 7, including asleeve surrounding said bearings, a yoke pivotally mounted on saidsleeve to tilt about an axis normal to the rotative axis, the cams beingtiltable about that axis and being secured to said yoke to be tiltedthereby, and a tilting arm carried by said yoke extending generally in adirection parallel to the rotative axis, the whole constituting themeans for tilting said yoke and cams.

References Cited in the iile of this patent UNITED STATES PATENTS

